1. + Electromagnetic Radiation The Electromagnetic Spectrum

2. + Electromagnetic waves can have a wide variety of frequencies The entire range of electromagnetic wave frequencies is known as the electromagnetic spectrum

3. + The Electromagnetic Spectrum Radio waves are low-frequency electromagnetic waves with wavelengths from less than a centimeter to about 1000 meters Even though radio waves carry information that a radio uses to create sound, you cannot hear radio waves You hear a sound wave when the compressions and rarefactions that sound wave produces reach your ears A radio wave does not produce compressions and rarefactions as it travels though air.

4. + The Electromagnetic Spectrum Microwaves are radio wavelengths of about 1 to 10 cm Microwave ovens heat food when microwaves interact with water molecules in food. The vibrating electric field inside a microwave oven causes water molecules in food to rotate back and forth billions of times each second This rotation causes a type of friction between water molecules that generates thermal energy.

5. + The Electromagnetic Spectrum In radar, radio waves bounce off an object to determine its speed and location Radar stands for RAdio Detecting And Ranging In Magnetic Resonance Imaging (MRI), radio waves produce an image of the inside of the body. MRI uses radio waves to help diagnose illness

6. + The Electromagnetic Spectrum Infrared waves are electromagnetic waves with a slightly higher frequency than radio waves; people feel them as thermal energy or warmth You use infrared waves every day A remote control emits infrared waves to control your television Every object emits infrared waves

7. + The Electromagnetic Spectrum Visible light has wavelengths between about 390 to 770 billionth of a meter and can be seen with the eye Your eyes contain substances that react differently to various wavelengths of visible light, so you see different colors. These colors range from short-wavelength blue to long wavelength red If all the colors are present, you see the light as white.

8. + The Electromagnetic Spectrum Ultraviolet waves have frequencies slightly higher than visible light and can damage skin Overexposure to ultraviolet rays can cause skin damage and cancer Most of the ultraviolet radiation that reaches Earth’s surface are longer-wavelength UVA rays The shorter-wavelength UVB rays cause sunburn, and both UVA and UVB rays can cause skin cancers and skin damage such as wrinkling

9. + The Electromagnetic Spectrum Ultraviolet light can kill bacteria When ultraviolet light enters a cell, it damages protein and DNA molecules Ultraviolet light can be absorbed by some fluorescent materials and released as visible light Police detectives sometimes use fluorescent powder to show fingerprints when solving crimes

10. + The Electromagnetic Spectrum The ozone layer above Earth’s surface absorbs most of the Sun’s harmful ultraviolet waves However, the decrease in ozone is caused by the presence of certain chemicals, such as CFCs, high in Earth’s atmosphere CFCs are chemicals called chlorofluorocarbons that have been widely used in air conditioners, refrigerators, and cleaning fluids

11. + The Electromagnetic Spectrum X rays and gamma rays are ultra- high-frequency electromagnetic waves that can travel though matter, break molecular bonds, & damage cells X rays are used to provide images of bones and to examine suitcases at airports without opening them Radiation therapy is used to kill diseased cells and can use both x rays and gamma rays